1. Field of the Invention
The present invention relates to a weather strip capable of sealing a gap between an opening of an automobile body or the like, and an opening/closing member for opening and closing the opening, and a production method thereof.
2. Related Art
Conventionally, a weather strip is installed at an edge portion of an opening which is formed in a body (automobile body) of an automobile or the like. The weather strip includes a trim portion of a substantially U-shaped cross section serving as a mounting base portion mounted on a flange portion which is provided along the edge portion of the opening, and a hollow sealing portion protruding from the trim portion and having a hollow portion. When an opening/closing member for opening and closing the opening is closed, a gap between the body and the opening/closing member is sealed by the pressing contact between the hollow sealing portion and the edge portion of the opening/closing member.
Such a kind of weather strip is formed in an annular shape or a further elongated shape by connecting ends of one or more extrusion molded portions, which are formed in an elongated shape by injection molding, side by side. That is, in a state in which the ends of the extrusion molded portions are supported and fixed in a molding device, an injection molded portion is formed between the ands by injection molding, so that the ends are connected to each other to form the weather strip of the annular shape or elongated shape.
In a weather strip having the hollow sealing portion, as described above, it is necessary to dispose a core mold for forming the hollow portion in a cavity of the molding device, at the time of forming the injection molded portion. The core mold includes a core body for forming the hollow portion, and a holding portion protruding outwardly from the core body. The core body is mostly enclosed by an elastic material such as rubber, but after formation of the injection molded portion, it is necessary to withdraw the core body from the hollow sealing portion of a molding product.
For this reason, the related art necessitates that the hollow sealing portion in the vicinity of the end of the extrusion molded portion be provided with an opening, through which the core body is withdrawn, that is, “core withdrawing hole” (for example, refer to JP-UM-A-59-169929). In such a configuration, a process of forming the core withdrawing hole is required before the injection molded portion is formed. In addition, the core body is disposed via the core withdrawing hole therebetween, and then the other end of the hollow sealing portion of the extrusion molded portion is to be inserted into a front end of the core body. Therefore, there may be a problem in that if the front end of the core body is formed in a taper shape in view of ease of insertion, an insertion margin and a width of the injection molded portion are widened thereby lowering the productivity or increasing the cost.
In contrast, a technique or the like, in which the ends of the extrusion molded portions face each other across a sheet material serving as an adhering member, and are bonded to each other by thermal processing, is proposed (for example, refer to JP-A-2000-263649). Such a configuration can reduce the width dimension of a connecting portion, but since the hollow portion is clogged in the connecting portion, a load may be locally increased in the vicinity of the connecting portion when the opening/closing member is closed. In addition, it is necessary to accurately perform the length adjustment of the extrusion molded portion or the positioning of the end in accordance with the thickness of the sheet material. Further, since a groove of the trim portion or the like is clogged, a process of cutting the sheet material after the bonding process is inevitable. Therefore, a problem such as a decrease in productivity or an increase in cost may occur. In addition, a stepped portion is likely to form between the extrusion molded portion and the connecting portion, and there is a fear of a reduction of sealing capability.
As a technique capable of suppressing the decrease in productivity or the increase in cost as compared with the related arts, a technique of providing a core withdrawing hole in a region of the injection molded portion is also disclosed (for example, JP-A-7-164978).
However, in the weather strip disclosed in JP-A-7-164978, since the width (connecting width) of the injection molded portion in the longitudinal direction of the weather strip is relatively long, and the opening, which is used as an air discharging hole, as well as the core withdrawing hole, formed in the injection molded portion has a relatively large opening area, there is a concern that it may look unattractive, and the quality of the appearance is deteriorated.
In addition, since the large opening is formed in the injection molded portion, there is a concern that a load difference may be increased between the injection molded portion and the extrusion molded portion in the vicinity of the injection molded portion when the opening/closing member is closed, the sealing capability is deteriorated.
Further, in order to prevent the load difference from being increased, the weather strip disclosed in JP-A-7-164978 is provided with a support lip for supporting the hollow sealing portion and closing the opening when the opening/closing member is closed. If such a support lip is provided, it may be difficult to carry out the core withdrawing operation.
In a case where the hollow sealing portion exists at a lateral surface of the trim portion, as the present invention, and a portion of the hollow sealing portion forms a sidewall of the trim portion, a portion of the core body which is provided in the hollow sealing portion forms the sidewall of the trim portion, and the trim portion is formed to have a thickness sufficient to maintain the shape thereof. Therefore, since the working of withdrawing the core body depends only on the deformation of the sealing wall side of the hollow sealing portion, it is difficult to carry out the core withdrawing operation.